Correctly positioned seems to just be train not overlapping ends of platform, which at most Northern stations is never going to be issue as the platforms are much longer than the trains. At stations with a 'Harrington hump' they release the doors as normal even if the doors aren't correctly lined up with the hump.
But the guard is still required to:
- confirm the train is in the correct location;
- release the doors.
Clearly moving to driver open guard close would remove this activity and would save *some* time at each and every stop (albeit the saving would vary by location).
I’m therefore unclear why you think this system makes
more sense for intercity services, which may only stop 3 or 4 times per journey, than for local services stopping perhaps 10-15 times in a short period?
It strikes me that the objective of freeing up guards to flog more tickets could have been partially achieved by moving to this system. This might have also avoided the recent industrial action!